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BlacK_Chicken 6th November 2005 03:47 PM

PCB cerrection for "Red Circuits Mosfet design" please!

I do need an amplifier for a powersupply rated at +-48V. I chose the Red Circuits Amp60 for my purpose, ich should be a reliable design (hope so).


As I dislike Amps build without Pcb for myself, and not for testing pupose I started to design a small PCB layout, single layer.

The goal was to fit 2 amps on a 100x160mm board (this is standard)

The Mosfets are mounted under th board, as shown.

The Program I used is probably 10 years old, but I like it alot, it is impossible to rotate I had to build my own for some pieces.

The Fuses should be before the driving stage, I know, but before havinf none I placed them there (smallest possible). I hope groundung is OK.

Here is a preview with some annotations, please give your comment and tell me if you see any errors!

surly there is a second version with thicker lines etc...this is just to see the original layout!

Thanks for your help!


Eva 6th November 2005 06:08 PM

Your single ground layout is probably going to cause humm. Two independent ground leads should be employed instead, one for signal and other for supply decoupling,. Also, it's quite usual to lousy couple both grounds in the PCB by means of a 47 or 100ohm resistor to avoid potential problems at RF due to ground wire inductance.

Concerning the layout itself, ideally power supply decoupling capacitors, power traces, fuses, and power and speaker connections should be placed all together near the output devices, trying to make current loops with the smallest area. On the other hand, the small signal stuff may be located in the opposite side of the PCB so that the input stage is well away from high current paths.

BlacK_Chicken 6th November 2005 09:02 PM


thanks a lot for your answer!

I had a look at various other layouts. The grounding is almost the same, I tried a star-ground.

Speaker Out, the fuses, the powertransistors and the powertraces are all together, exept for the small on-board decoupling Caps (100u) wich are near my Grund-line. Putting them nearer to the Outputstage (what I originally thought of) caused greater grounding Probs.

I may overthink my layout once again. Any other thoughts?


PS: Sorry for the mistakes in my writing!

Eva 7th November 2005 02:15 PM

Do it as the picture on the first post of that thread suggests:

Also, you should move the decoupling capacitors, they should be placed as close to the output devices as possible.
This is a picture of the unfinished layout of a two channel amplifier with two pairs of output devices and drivers per channel. The input stage is in a separate daughter board far away from the output stage. It shows more or less what I was explaining in my previous post about current loops. C3 and C4 are the supply decoupling capacitors. Note how the high current stuff is tightly packed and concentrated.

dmartin 21st September 2007 05:57 PM


Somebody has a good version of this pcb?


Giaime 21st September 2007 09:11 PM

Ehm, sorry. But did you know that here exist tons of topics about the faults of that design? It won't be reliable, it will burn down.

See here:

and others I couldn't find but I remember them.

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